Author Topic: Need analog temperature receiver  (Read 3537 times)

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Offline ccronan

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Need analog temperature receiver
« on: November 22, 2008, 12:34:10 AM »
Hello,

I need to set up a wireless outdoor thermometer but the receiver has to provide an analog output (voltage).  The output is not destined for a computer but can be used as such.  I am designing a prototype device to capture analog outdoor temperature data.  My inquiries to manufacturers have not been helpful.  I have been told to "buy a device to see if the internal circuitry might provide an analog signal and, oh by the way, taking the device apart cancels any warranty".  Right.
 
I am hoping that someone can recommend a manufacturer (and model) of such devices, hopefully cheap and accurate (as we all hope for).  At first it will be fed to a data acquisition module (I found one for $25).  A weather station is overkill for this application, and I don't think one would be inexpensive enough to fill my need.  Ultimately I want to run some statistical analyses of this data.

I am in WI so I would need a range of -30F to 110F.

Any help here?

Thanks.

Offline wuhu_software

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Re: Need analog temperature receiver
« Reply #1 on: November 22, 2008, 12:46:04 PM »

If you want to monitor a single location, you can get a La Crosse for $80 and upload the data to Weather Underground.

You could find cheaper solutions if you are willing to drill a hole in your exterior wall.


Offline ccronan

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Re: Need analog temperature receiver
« Reply #2 on: November 22, 2008, 02:32:02 PM »
Hi,

I don't understand how that would get me an analog (not digital and not from a computer) outdoor temperature.   I understand that this is unusual to ask today, but before computers became readily available, they had to exist.  One that would have worked would attach to a voltmeter, for example, or feed into an A/D module.

Also, drilling a hole for wiring is not possible.

I don't want to abandon this suggestion either.  Do you have a La Crosse model number?

Thanks, but I need more suggestions.  I am stuck.

Offline SLOweather

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Re: Need analog temperature receiver
« Reply #3 on: November 22, 2008, 04:06:42 PM »
Unless you are using an analog meter to read the temperature, it's all going to end up as digital anyway.

Having said that, google on analog temperature sensor and you will find all manner of temp sensors. Here are some from Maxim:

http://www.maxim-ic.com/products/sensors/analog_sensors.cfm

Offline wuhu_software

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Re: Need analog temperature receiver
« Reply #4 on: November 22, 2008, 04:10:26 PM »

I would recommend at WS-2316 that comes with a cup style wind sensor.

The WS-2308 is almost identical but has a tiny turbine type wind sensor. Most people do not care for this sensor.

Costco runs specials now and then, usually store only, for under $80.


Offline ccronan

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Re: Need analog temperature receiver
« Reply #5 on: November 23, 2008, 02:00:11 AM »
SLOweather,

The temperature signal is NOT going into a computer (initially it will be, for testing only), and I really, really need a voltage signal, not digital.  Actually it won't be read at an analog meter either (although it could if I ever find my ideal sensor).

Those search terms bring up a lot of data.  "wireless thermometer analog receiver" would be ideal.  With your suggestions I found some industrial devices, a little too pricey. 

I am building a device, computer-free and unprocessed by computer, that will perform a function based upon an average temperature.  Can't say much more than that, except it will be built around an analog (voltage) wireless thermometer if one exists.  My electronic abilities can handle analog, not digital.  And it certainly could be easily accomplished with a thermocouple hard-wired from the outside but that is not wireless, one necessary requirement.

I may have to teach myself some digital electronics, might be easier if I can't find an OTC analog version.  That information could probably be obtained by modifying a digital unit (warranty no longer valid).

Thanks for all the comments.

Offline SLOweather

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Re: Need analog temperature receiver
« Reply #6 on: November 23, 2008, 10:50:18 AM »
I'm not sure how one would create a wireless analog temp sensor. The temp would have to be sent as some continuously varying analog value. About the only thing that comes to mind is an audio frequency. For your stated 140 degree F range, and, say a 2000 Hz range, you could get 15 Hz per degree. The process would be complicated by trying to temperature-compensate all of the tone generating electronics so that only the sensor affects the frequency.

Everything commercial and wireless is going to be digital. At the receiving end, you could re-convert it back to analog, but then you will still be limited by the resolution of the digitization process, the number of bits in the value.

What other design constraints do you have? Battery power? Size?

Offline ccronan

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Re: Need analog temperature receiver
« Reply #7 on: November 25, 2008, 10:11:46 PM »
SLOweather,

It looks more and more as though I will have to reconvert from digital to analog, or drill a hole in the window frame (actually this latter option will never happen).  8 bits can get me 3/4 of a degree, 10 bits about 0.1F accuracy.  It would have to be at least 10 bits.

For my app, I need two sensors; the first one I have.  The temperature, which I thought was to be easier, looks very difficult.  This device is supposed to be for the common, non-technical person without tying up a PC, and placing a wireless outdoor thermometer is as difficult as I want it to be.

I thank you for your comments and straightening out my thoughts.  You were very helpful, and I appreciate your time.  I think the concept now has to be reworked.

Chuck

Offline SLOweather

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Re: Need analog temperature receiver
« Reply #8 on: November 25, 2008, 11:00:16 PM »
Thanks for the feedback, ccronan. So often, we answer here or on other forums, and never get the final resolution from the asker. I'm pleased I could be of assistance.

It's nice to be appreciated. If you have any more questions, I'd be glad to help, here, off forum, and/or under NDA.

Chris


SLOweather,

It looks more and more as though I will have to reconvert from digital to analog, or drill a hole in the window frame (actually this latter option will never happen).  8 bits can get me 3/4 of a degree, 10 bits about 0.1F accuracy.  It would have to be at least 10 bits.

For my app, I need two sensors; the first one I have.  The temperature, which I thought was to be easier, looks very difficult.  This device is supposed to be for the common, non-technical person without tying up a PC, and placing a wireless outdoor thermometer is as difficult as I want it to be.

I thank you for your comments and straightening out my thoughts.  You were very helpful, and I appreciate your time.  I think the concept now has to be reworked.

Chuck

Offline Bushman

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Re: Need analog temperature receiver
« Reply #9 on: November 28, 2008, 04:46:03 PM »
Have you considered using a thermistor?  I have a remote monitoring system that uses 2.2K thermistors that deliver resistance that the unit converts to temp.  Pretty straightforward.

 

anything